Omega-3 Fats
by author Karlene Karst, BSc, RD

Although the trend over the last 20 years has been toward a more “fat-free” diet, we now understand that the body needs essential fatty acids to control a large number of cellular processes. Since essential fatty acids are not produced naturally in the body, they must be obtained through food and nutritional supplements.

Research with essential fatty acid supplementation has shown promise in a number of areas, including cardio-vascular health, diabetes, rheumatoid arthritis, skin conditions, brain function, infant development, immune function, and cancer prevention. The benefits of omega-3 fatty acids for cardiovascular disease have been well documented and studied.

Evidence of the protective powers of omega-3 fatty acids found in fish oil is so strong that the American Heart Association (AHA) now urges everyone to eat at least two 3-ounce servings of fish a week. In the fall of 2002, the AHA advised people who already have heart disease to consume about one gram a day of the active ingredients in fish oil - eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). This is one of the few times that a major health organization has endorsed any dietary supplement for treating or preventing disease.

Vegetarian Sources of Omega-3

For vegetarians, and those who dislike the taste of fish, have a fish allergy, or are just unable to tolerate fish oil due to reflux, plant sources of omega-3 fatty acids are preferable. Plant-based omega-3s, including flax seed, perilla, and other nuts and seeds, are excellent alternatives to marine-based omega-3s.

Vegetarian omega-3s are rich in the essential fatty acid alpha linolenic acid (ALA), which has many substantiated health benefits. ALA is converted through our metabolic pathways into EPA and DHA. Although the scientific community continues to debate the conversion rate, generally 10 to 15 percent of ALA will be converted into longer chain omega-3s. This rate is highly affected by diet, environment, and lifestyle factors; for example, diets high in saturated and trans fats, smoking, and stress will slow this conversion.

One of the most significant landmark studies examining the relationship between dietary ALA and heart disease - the Nurse’s Health Study - followed the dietary habits of more than 120,000 registered nurses for more than 10 years. Nurses with the highest dietary intake of ALA experienced 30-percent fewer fatal heart attacks than those who consumed lower amounts of ALA, according to the June 1997 New England Journal of Medicine.

Similarly, the population of Kohama Island in Japan has the longest life expectancy in the world and the lowest death rate due to coronary heart disease, according to the 1982 Journal of Nutritional Science and Vitaminology. This population has the highest blood levels of ALA compared to other populations.

ALA has many important heart health benefits and research has also shown immune system improvements upon supplementation with ALA.

Omega-3s and Their Sources

Omega-3 fatty acids are the fastest growing segment of the health and nutrition supplement market, with fish oil sales showing an impressive 44-per-cent growth rate. ALA is found in highest amounts in flax seed and perilla seeds, and in small amounts in some nuts (especially walnuts), green leafy vegetables, canola, wheat germ, and black currant seeds. Flax seed has high oil content (35 to 44 percent) and flax seed oil contains 50 to 60 percent ALA. Perilla seed oil also contains between 50 and 64 percent ALA.

EPA and DHA are found in variable amounts in fish with the highest amounts being found in fatty, cold-water fish, such as sardines, anchovies, mackerel, salmon, and tuna. Depending on the source of the fish used, fish oils vary in the amount of EPA and DHA they provide. For instance, tuna oil typically contains five-per-cent EPA and 25-per-cent DHA, whereas salmon oil provides six-percent EPA and nine-per-cent DHA.

Algal sources of EPA and DHA are also widely available.

Quality of Omega-3 Supplements

Omega-3s have substantial research to prove their efficacy; however, having a quality oil supplement is also important to ensuring the highest purity and potency of omega-3s. Some consumers are concerned about contamination by heavy metals and other environmental contaminants such as dioxins and PCBs, especially from fish that can accumulate many of these toxins during their life span. Supplements have this advantage over consuming fish - fish oil supplements available on the market because the former have been purified to remove any contaminants and heavy metals, and have been tested to meet industry standards for these toxins. It is important to let your health food retailer know that you want to purchase a supplement that has been tested for heavy metals and other contaminants, because quality is important.

Have You Had Your Omega-3s Today?

With all the substantiated research in the area of omega-3s for health, it is essential that we fill our plates with fatty fish such as salmon, tuna, and mackerel, and consume flax and other nuts and seeds. Those who find it difficult to consume omega-3 rich foods because they dislike fish or have nut allergies, and those who require higher dosages than traditional foods offer, may find high-quality, may find omega-3 rich supplements are a convenient way to ensure you are getting the omega-3s your body craves.

To avoid minor side-effects, such as stomach upset, loose stools, and bloating, take the oil with meals, start with smaller doses, and work up to the larger therapeutic dose.

Omega-3s per 100g Serving of Fish

Cod, haddock, halibut	less than 0.5 g
Salmon	1 to 1.5 g
Herring, lake trout	1.5 to 2 g
Sardines, mackerel	2 to 3.3 g

Karlene Karst, BSc, RD, is a specialist in nutritional education and provides educational seminars, lectures, and regulatory advice on essential fatty acids. She recently co-authored the book Healthy Fats for Life (Quarry Books, 2003).

Source: alive #256, February 2004